1. Field of the Invention
The present invention relates to a data recording and reproducing apparatus such as digital audio tape recorder (DAT) for combining and recording signals in plural channels, and reproducing the recorded signals by individual channel.
2. Description of the Related Art
As one of the conventional apparatus for recording and reproducing data, a DAT converts an audio signal into a digital signal for recording on a magnetic tape, and converts the digital signal recorded in the magnetic tape into an audio signal.
Information for error correction, such as parity, can also be recorded. Therefore the original sound can be reproduced at high fidelity, and sound reproduction at a very low noise level is realized.
In some of the products of the conventional DAT, it is either of two-channels or four channels which can be selected: in a two-channel mode of operation two channels individually record two kinds of audio signals on the magnetic tape, or in a four-channel mode, four channels individually record four kinds of audio signals on the magnetic tape.
In the two-channel mode, two kinds of audio signal corresponding to two speakers disposed at the front left side and front right side of the listener are recorded in the magnetic tape, and in the four-channel mode, four kinds of audio signal corresponding to four speakers disposed at the front left side, front right side, rear left side and rear right side of the listener.
In the four-channel mode, hitherto is known a method of DAT (the Japanese Unexamined Patent Publication (KOKAI) No. JP-A 1-267870(1989)) for recording audio signals in two channels and still picture video signals in the other two channels, and reproducing audio signals and video signals simultaneously from one magnetic tape. In this DAT system, for example, two image memories are prepared for storing the video signals of one screen, and when recording, the video signals of one screen are sequentially written during a specific time period (hereinafter called the first period) in one of the image memories before being recorded in the magnetic tape, and the video signals are read out from the same image memory in a specific time period (the second period) longer than the first period and recorded onto the magnetic tape.
At this time, the audio signal corresponding to the video signal is, before being recorded in a magnetic tape, sequentially written in the remaining area image memory not used for writing of video signal in the second period, and, after completion of writing, is read out from the image memory in the same second period and recorded in the magnetic tape.
Consequently, in the magnetic tape, the still picture video signals for one screen and the corresponding audio signals of narration or the like are recorded as a pair in one block. That is, in the first half recording region of one block, the still picture video signals are recorded, and in the latter half recording region, the audio signals are recorded.
When reproducing, the video signals for one screen read out from the magnetic tape are written sequentially into one of the image memories in the second period. After completion of writing, the video signals for one screen are read out and reproduced from the image memory in the first period.
At this time, the audio signals read out from the magnetic tape next to the video signals are reproduced in the second period. Accordingly, when the still picture video signals for one screen are reproduced, the audio signals of the narration or the like corresponding to the still picture are reproduced in parallel.
In this DAT, when reading and reproducing an arbitrary video signal, the desired video signal is searched on the basis of sub-code data (frame number, chapter number, etc.) which are identification information recorded on the magnetic tape together with the video signal. The video signal is read out from the searched recording region and reproduced. This searching action is executed even while reproducing the magnetic tape. That is, the recording region in which the video signal being presently reproduced is recognized on the basis of the sub-code data, and the magnetic tape is fast-forwarded or rewound up to the recording region where the video signal desired to be reproduced is recorded.
Therefore, for example, if the present reproducing position is near the end of a magnetic tape, and the video signal to be reproduced is recorded near the beginning of the magnetic tape, the magnetic tape rewinding time is long. For example, in the case of a 46-minute tape, it takes about 30 seconds. Accordingly, while searching the magnetic tape, the video signal being reproduced just before is kept in display, or a blue screen is displayed in a so-called blue back state.